Technical Considerations for the Generation of Adoptively Transferred T Cells in Cancer Immunotherapy

Lymph nodes may be a source for immunetherapy in gastric cancer

BACKGROUND

adoptive immunotherapy is a promising cancer therapy. Immune cells are capable of recognizing and destroying cancer cells and represent a powerful strategy, however, this approach remains technically complicated, due to the need to select and isolate immune cells from these, present cancer antigens to those cells, expanding and reinjecting them. Lymph nodes recovered during gastric cancer surgery may represent an option for immunotherapy, since they harbor an enormous amount of immune cells, which have already been presented to cancer antigens. The advantage of selecting only cancer-negative lymph has not been determined yet. The status of immune checkpoints in the immune cells within the lymph nodes was analyzed in order to try to solve this problem.

MATERIALS AND METHODS

Tissue microarrays were constructed and automated immunostaining for PD-1 and PD-L1 was performed on 143 lymph nodes from 70 patients with gastric adenocarcinoma.

RESULTS

In positive nodes, PD-L1 was only positivity in cancer cells (6%) and PD-1 was positive for B lymphocytes (60%), T lymphocytes (70%) and one case in cancer cells (2.5%). In negative nodes, most cases were positive for PD-1 in B (73.1%) and T (71.65%) lymphocytes.

CONCLUSIONS

Expression of PD-1 and PD-L1 in gastric cancer lymph nodes was demonstrated for the first time. PD-1 is expressed in positive and negative nodes, which could activate the PD-1 pathway. Lymphocytes from tumor-free lymph nodes were negative for PD-L1, and this might represent an advantage for selecting these lymph nodes as a potential source of immune cells for adoptive immunotherapy.

Scale-up of the ex vivo expansion of encapsulated primary human T lymphocytes

A number of evolving medical therapies call for the controlled expansion of primary human T lymphocytes. After encapsulation in sodium cellulose sulfate-poly(diallyldimethyl) ammonium chloride polyelectrolyte capsules, T lymphocytes can be expanded without persisting activation. Here, the challenge of scaling up this process is addressed. Encapsulated T lymphocytes were cultured in spinner flasks as well as in several types of the bioreactor, including fixed and fluidized beds, a waved cell bag, and a standard stirred tank reactor (STR; 1-L scale). Two proprietary T lymphocyte culture media as well as a standard RPMI-based medium were used. As before, encapsulation coincided with the presence of only a low fraction of activated T lymphocytes (peripheral blood T cells) in the total population. Unexpectedly, growth rates were lower in well-mixed reactors than those in cultivations under static conditions, that is, in T-flasks. Switching the STR to low oxygen conditions (40% air saturation) improved the growth rates to the level of the static cultures and thus forms the potential basis for efficient scale-up of T lymphocyte expansion.

Prospects for combined use of oncolytic viruses and CAR T-cells

With the approval of talimogene laherparepvec (T-VEC) for inoperable locally advanced or metastatic malignant melanoma in the USA and Europe, oncolytic virotherapy is now emerging as a viable therapeutic option for cancer patients. In parallel, following the favourable results of several clinical trials, adoptive cell transfer using chimeric antigen receptor (CAR)-redirected T-cells is anticipated to enter routine clinical practice for the management of chemotherapy-refractory B-cell malignancies. However, CAR T-cell therapy for patients with advanced solid tumours has proved far less successful. This Review draws upon recent advances in the design of novel oncolytic viruses and CAR T-cells and provides a comprehensive overview of the synergistic potential of combination oncolytic virotherapy with CAR T-cell adoptive cell transfer for the management of solid tumours, drawing particular attention to the methods by which recombinant oncolytic viruses may augment CAR T-cell trafficking into the tumour microenvironment, mitigate or reverse local immunosuppression and enhance CAR T-cell effector function and persistence.